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  • 1.
    Diószegi, Attila
    et al.
    Jönköping University, School of Engineering, JTH. Research area Materials and Manufacturing - Casting. Jönköping University, School of Engineering, JTH, Mechanical Engineering.
    Elmquist, Lennart
    Jönköping University, School of Engineering, JTH. Research area Materials and Manufacturing - Casting. Jönköping University, School of Engineering, JTH, Mechanical Engineering.
    Orlenius, Jessica
    Jönköping University, School of Engineering, JTH. Research area Materials and Manufacturing - Casting.
    Dugic, Izudin
    Jönköping University, School of Engineering, JTH. Research area Materials and Manufacturing - Casting.
    Defect Formation at Casting of Gray Iron Components2009In: Proceedings of the Carl Loper Cast Iron Symposium, Madison, Wisconsin, US, 2009Conference paper (Refereed)
  • 2.
    Eckert, Gunnar
    et al.
    Jönköping University, School of Engineering, JTH, Mathematics.
    Hjelmåker, Monica
    Jönköping University, School of Engineering.
    Elmquist, Lennart
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Off campus integrating theory and practice with progression2013Conference paper (Other academic)
  • 3.
    Elmquist, Lennart
    Jönköping University, School of Engineering, JTH. Research area Materials and Manufacturing - Casting.
    Defect Formation during Solidification in Grey Iron Castings2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The presence of defects is of major concern in the production of grey iron castings. Some defects are merely an aesthetic problem while others can be detrimental for the performance of the component. Among the several possible defects, shrinkage porosity is one of the more challenging to understand and avoid. This type of defect can penetrate through the casting as a three-dimensional network. The purpose of this work has been to develop knowledge and understanding about the foundry process in order to increase product quality by eliminating or at least minimising the presence of shrinkage porosity in the production of vital engine components. This was done by developing fundamental knowledge concerning factors known to influence the presence of shrinkage porosity.

    Initially, an investigation was carried out in order to characterize shrinkage porosity commonly occurring in cylinder heads. Factors found to be important and contributing to the formation of shrinkage porosity were identified. It was found that this type of defect is formed at hot spots that have migrated during solidification. Knowledge of the migrating hot spot was used as a design criterion in the development of a geometry with the purpose of deliberately generating porosity. Based on this geometry a mechanism for the formation of this type of shrinkage porosity was proposed.

    The formation of shrinkage porosity depends on gases dissolved in the melt. In this work, their levels and variations in the melting process were investigated. It was shown how the solubility of oxygen depends on the temperature but not on the method used to produce the iron. On the other hand, the total amount of oxygen depends on the process but not on temperature. The discussion about gases also included hydrogen and nitrogen.

    The solidification of grey cast iron is complex. It is during the solidification that not only the final properties of the component but also the conditions for defect formation are established. Shrinkage porosity is formed due to volumetric changes followed by an inability to supply material to the contracting areas. The solidification of grey iron starts with nucleation and growth of the primary austenite followed by nucleation of eutectic cells. It was found that the microstructural constituents are interconnected. The importance of the macrostructure was also discussed and it was shown that shrinkage porosity can be found not only between eutectic cells but also between equiaxed crystals.

  • 4.
    Elmquist, Lennart
    Jönköping University, School of Engineering, JTH. Research area Materials and Manufacturing - Casting.
    Factors Influencing the Formation of Shrinkage Porosity in Grey Cast Iron2008Licentiate thesis, comprehensive summary (Other academic)
  • 5.
    Elmquist, Lennart
    et al.
    Jönköping University, School of Engineering, JTH, Mechanical Engineering. Jönköping University, School of Engineering, JTH. Research area Materials and Manufacturing - Casting.
    Diószegi, Attila
    Jönköping University, School of Engineering, JTH, Mechanical Engineering. Jönköping University, School of Engineering, JTH. Research area Materials and Manufacturing - Casting.
    Influence of Solidification on the Primary Austenite Structure of Grey Cast Iron2008Report (Other academic)
    Abstract [en]

    In this work, the influence of cooling rate, chemical composition and inoculation practice on the solidification of grey cast iron has been examined. The primary solidification structure, referred to as the macrostructure, was preserved using a special heat treatment, DAAS (Direct Austempering After Solidification). These samples were etched and the number of equiaxed and columnar crystals as well as the transition between these areas, CET, was examined quantitatively. Samples considered As-Cast were colour etched to reveal the microstructural constituents. On these samples the number of eutectic cells, fraction of primary austenite and DAS (Dendrite Arm Spacing) was investigated. The relationship between CET and the number of equiaxed crystals was confirmed, and decreases with increasing number of equiaxed crystals per unit volume. It was also found that the number of equiaxed chemical composition. Furthermore, there is a relationship between eutectic cells and DAS; where the eutectic cell size increases with increasing DAS. DAS, on the other hand, depends on inverse cooling rate and the number of equiaxed crystals.

  • 6.
    Elmquist, Lennart
    et al.
    Jönköping University, School of Engineering, JTH. Research area Materials and Manufacturing - Casting. Jönköping University, School of Engineering, JTH, Mechanical Engineering.
    Diószegi, Attila
    Jönköping University, School of Engineering, JTH. Research area Materials and Manufacturing - Casting. Jönköping University, School of Engineering, JTH, Mechanical Engineering.
    On the Problems of a Migrating Hot Spot2010In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 649, p. 443-448Article in journal (Refereed)
  • 7.
    Elmquist, Lennart
    et al.
    Jönköping University, School of Engineering, JTH. Research area Materials and Manufacturing - Casting. Jönköping University, School of Engineering, JTH, Mechanical Engineering.
    Diószegi, Attila
    Jönköping University, School of Engineering, JTH. Research area Materials and Manufacturing - Casting. Jönköping University, School of Engineering, JTH, Mechanical Engineering.
    Shrinkage Porosity and its Relation to Solidification Structure of Grey Cast Iron Parts2010In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 23, no 1, p. 44-50Article in journal (Refereed)
  • 8.
    Elmquist, Lennart
    et al.
    Jönköping University, School of Engineering, JTH, Mechanical Engineering. Jönköping University, School of Engineering, JTH. Research area Materials and Manufacturing - Casting.
    Diószegi, Attila
    Jönköping University, School of Engineering, JTH, Mechanical Engineering. Jönköping University, School of Engineering, JTH. Research area Materials and Manufacturing - Casting.
    The relation between SDAS and eutectic cell size in grey iron2010In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 23, no 4, p. 240-245Article in journal (Refereed)
  • 9.
    Elmquist, Lennart
    et al.
    Jönköping University, School of Engineering, JTH. Research area Component Technology. Jönköping University, School of Engineering, JTH, Mechanical Engineering.
    Diószegi, Attila
    Jönköping University, School of Engineering, JTH. Research area Component Technology. Jönköping University, School of Engineering, JTH, Mechanical Engineering.
    Adolfsson, Stefan
    Characerizing Shrinkage Porosity in Gray Cast Iron using Microstructure Investigation2008In: Transactions of the American Foundry Society: volume 116 ; One Hundred Twelfth Annual Metalcasting Congress, May 17-20, 2008, Schaumburg, Ill.: American Foundry Society , 2008, Vol. 116, p. 691-703Conference paper (Other academic)
  • 10.
    Elmquist, Lennart
    et al.
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Diószegi, Attila
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting. Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Björklind, Tobias
    On the Formation of Shrinkage Porosity in Gray Iron Castings2011In: Key Engineering Materials, ISSN 1013-9826, E-ISSN 1662-9795, Vol. 457, p. 416-421Article in journal (Refereed)
    Abstract [en]

    The formation of shrinkage porosity is a concern in the production of high-quality gray iron castings. In this work, a geometry known to generate this type of defect was used to investigate some of the parameters that influence its formation. The geometry is based on the presence of a migrating hot spot that at the end of the solidification is located close to the interface between the casting and the mold. The occurrence of shrinkage porosity at this position was investigated and the cavities examined using a scanning electron microscope equipped with EDS. It is believed that this type of defect is in contact with the atmosphere during solidification. The risk for shrinkage porosity decreases with increasing carbon content. The effect of high levels of molybdenum and phosphorus was investigated and shown to influence the defect formation. Inoculation is used to control the nucleation and the effect of high levels of inoculants was also examined. The microstructure was investigated by the use of a color etching technique, and the quantification considered eutectic cell size and secondary dendrite arm spacing. The quantification was done on the microstructure in the vicinity of defects as well as in areas without porosity.

  • 11.
    Elmquist, Lennart
    et al.
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Diószegi, Attila
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Svidró, Peter
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Influence of Primary Austenite on the Nucleation of Eutectic Cells2011In: Key Engineering Materials, ISSN 1013-9826, E-ISSN 1662-9795, Vol. 457, p. 61-66Article in journal (Refereed)
    Abstract [en]

    The solidification of gray cast iron starts with the precipitation of primary austenite. This phase nucleates either as columnar or equiaxed dendrites depending on whether nucleation occurs on the mould wall or on particles and impurities in the melt. In this work, the nucleation of primary austenite and its influence on the eutectic solidification has been investigated using different amounts of iron powder as inoculants. Besides, the influence of different cooling rates was also examined. Within each austenite grain there is a microstructure, and this microstructure was investigated using a color etching technique to reveal the eutectic cells and the dendritic network. It is shown how the cooling rate affects the dendritic network and the secondary dendrite arm spacing, and how the microstructure can be related to the macrostructure through dendrite arm spacing. The secondary dendrite arm spacing is a quantification of the primary austenite belonging to the primary solidification, and it will be shown how the eutectic cell size is related to the secondary dendrite arm spacing. The total amount of oxygen influences the microstructural dimensions. This effect, on the other hand, is influenced by the cooling rate. The number of eutectic cells versus eutectic cell size show two distinct behaviors depending on whether being inoculated with iron powder or a mixture of iron powder and commercial inoculant. The addition of a commercial inoculant decreases eutectic cell size and increases the number of cells, while iron powder almost only changes cell size.

  • 12.
    Elmquist, Lennart
    et al.
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Eriksson, Lars
    Jönköping University, School of Engineering, JTH, Product Development. Jönköping University, School of Engineering, JTH. Research area Product Development - Industrial Design.
    Ekman, Fredrik
    Research and Development, Strömsholmen AB.
    Workshop at a company with students from two different disciplines2014Conference paper (Refereed)
    Abstract [en]

    Teachers from two different disciplines, Materials and manufacturing and Industrial design, are brought together to give a course on masters level. Also the students come from different disciplines. They study two different master programs in Product development, Product development and materials engineering and Industrial design. The course is called Materials and design, and it covers both disciplines. Apart from lectures, computer labs and home assignments, a workshop was arranged where the students during one day solved a task related to product development. The students were divided into groups in such a way that a mixture of students from the two programs was obtained. The workshop was held at a company in order to make the work more realistic. Before they started to solve the task, they were given an introduction to the products made by the company and their applications. The main task was then to investigate the products and come up with ideas about what applications there might be in the future. The result was at the end of the day presented to the company. In this paper, the workshop is described, and comments and reflections from the students and the company are summarized. Finally the teachers involved give their opinion about the result and the pedagogic benefits from such a workshop, and also what to think about for the next time. It appeared that the workshop was an eye-opener to the company at the same time as the students had a fair chance to work in a realistic situation and practice how to use their knowledge. Also for the teachers it was a good experience, not only from a pedagogic viewpoint but also on how to arrange this kind of workshops in the future.

  • 13.
    Elmquist, Lennart
    et al.
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Johansson, Glenn
    Jönköping University, School of Engineering, JTH. Research area Industrial Production.
    An approach to foster integrative skills during the engineering studies2011In: Conference proceedings, Technical University of Denmark , 2011Conference paper (Refereed)
    Abstract [en]

    This paper presents an approach to overcome the drawbacks associated with education programs developed on the basis of domain-specific knowledge only. The approach is based on establishment of means for cross-disciplinary meetings and collaboration between students on Master programs in product development and production management. The approach is intended to help reducing the barriers to integration among individuals possessing different competences that have been reported in the literature. The approach originates from discussions regarding two Master programs at the School of Engineering (JTH), Jönköping University, Sweden. The programs are: Master in Product Development, specialisation in Product Development and Materials Engineering and Production Systems, specialisation in Production Development and Management. Both programs are designed according to the principles of the CDIO initiative. The approach was developed jointly by the two Master program coordinators during a workshop at Stanford University on ‘Changing mindsets: Improving creativity and innovation’ in December 2010. The workshop was organised by the Swedish program ‘Product Innovation Engineering program’ (PIEp). The approach emerged during the workshop and was modelled as a physical prototype and discussed with other workshop participants. The result was three courses found to besuitable for joint studies.

  • 14.
    Elmquist, Lennart
    et al.
    Jönköping University, School of Engineering, JTH, Mechanical Engineering. Jönköping University, School of Engineering, JTH. Research area Component Technology.
    Orlenius, Jessica
    Jönköping University, School of Engineering, JTH, Mechanical Engineering. Jönköping University, School of Engineering, JTH. Research area Component Technology.
    Diószegi, Attila
    Jönköping University, School of Engineering, JTH, Mechanical Engineering. Jönköping University, School of Engineering, JTH. Research area Component Technology.
    Influence of Melting Process on Oxygen Content in Gray Iron2007In: Transactions of the American Foundry Society: One Hundred Eleventh Annual Metalcasting Congress May 15 - 18, 2007, Schaumburg, Ill.: American Foundry Society , 2007, Vol. 115, p. 625-636Conference paper (Refereed)
    Abstract [en]

    The amount of dissolved oxygen, as well as oxygen available as oxides, is considered to affect the nucleation and growth of porosity defects in gray iron castings. Therefore, the influence of melting process on oxygen content was investigated in the production at two foundries. The importance of temperature on the equilibrium between the melt and its surrounding was especially examined. It was found that the amount of dissolved oxygen decreased with decreasing temperature, but the total amount of oxygen remained unchanged, meaning that the amount of oxygen found as oxides increased as the temperature decreased.

  • 15.
    Elmquist, Lennart
    et al.
    Jönköping University, School of Engineering, JTH. Research area Materials and Manufacturing - Casting. Jönköping University, School of Engineering, JTH, Mechanical Engineering.
    Salera, Sebastian
    Diószegi, Attila
    Jönköping University, School of Engineering, JTH. Research area Materials and Manufacturing - Casting. Jönköping University, School of Engineering, JTH, Mechanical Engineering.
    Inoculation and its effect on primary solidification structure of hypoeutectic grey cast iron2010In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 23, no 2, p. 124-129Article in journal (Refereed)
    Abstract [en]

    The solidification of grey cast iron is controlled by the addition of inoculants. This is done in order to provide nucleation sites and hence facilitate the formation of eutectic cells and decrease the degree of undercooling. The number of eutectic cells and the graphite morphology affect the final properties of the casting. Preceding the nucleation of graphite and the eutectic cells is the nucleation of the primary austenite. It was found that the addition of inoculants also influences the primarysolidification. The largest effect on the primary dendrites is obtained by inoculation using pure ironpowder. It was also shown how the columnar to equiaxed transition (CET) depends on the number ofequiaxed dendrites per unit volume. In addition, the primary structure was found to influence the eutectic solidification. The relationship between the secondary dendrite arm spacing and the eutectic cell size was found to correlate well with the work of others.

  • 16.
    Elmquist, Lennart
    et al.
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Sonawane, Pankaj
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    On the relation between primary and eutectic solidification structures in gray iron2012Conference paper (Refereed)
    Abstract [en]

    The solidification of hypoeutectic gray cast iron starts with the nucleation of primary austenite crystals. Before graphite is nucleated, and the eutectic structure is formed, these crystals start to grow as columnar or equiaxed dendrites. However, very little is known about these dendrites, and especially how they influence the subsequent eutectic structure. Besides, it has previously been shown that the primary solidification structure influences the formation of defects. Shrinkage porosity was found between the dendrites, in the grain boundaries, and the formation of the primary solidification structure was found to influence problems related to metal expansion penetration. Therefore a better understanding about the formation of this structure is of importance. In this work, different inoculants and their influence on the formation of the micro- and macrostructures has been investigated. The inoculants considered are commercially used inoculants, i.e. inoculants used in the foundries, as well as different iron powders. The addition of iron powder is used to promote the primary solidification structure. It is shown that the nucleation of the dendrites is influenced by the amount of iron powder. Secondary dendrite arm spacing is a quantitative measurement in the microstructure related to these dendrites, which in turn depends on the solidification time. Eutectic cell size, on the other hand, is found to depend on secondary dendrite arm spacing. It is shown how the addition of inoculants influences both primary and eutectic solidification structures, and how they are related to each other.

  • 17.
    Ghasemi, Rohollah
    et al.
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Elmquist, Lennart
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting. Scania CV AB, Materials Technology, SE-151 87 Södertälje, Sweden.
    Cast iron and the self-lubricating behaviour of graphite under abrasive wear conditions2014Conference paper (Refereed)
    Abstract [en]

    Cast iron is assessed as a self-lubricating material under sliding conditions. This is due to the graphite particles distributed in the matrix, which come out from their pocket, and form a tribofilm between the mating surfaces, and by which improve the tribological characteristics. In this study, the directionality and the interaction between the graphite and matrix material was investigated by microindentation and microscratch techniques. The results showed that the graphite is fractured and pushed out from the middle of graphite lamellas as a result of indentation. It was also observed that the graphite orientation below the surface intensely influenced the pushing out behaviour. For the graphite oriented toward the indenter position, the effect was more pronounced. Moreover, it was found that a scratch test can be used to investigate and explain the graphite pushing out tendency. The result was used to explain the directionality and closing tendency of the graphite lamellas during sliding.

  • 18.
    Ghasemi, Rohollah
    et al.
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Elmquist, Lennart
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    The relationship between flake graphite orientation, smearing effect, and closing tendency under abrasive wear conditions2014In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 317, no 1–2, p. 153-162Article in journal (Refereed)
    Abstract [en]

    Abstract Plastic deformation of the matrix during the wear process results in closing the graphite flakes. In this study, the relationship between the deformation of the matrix and the closing tendency of flake graphite was investigated, both qualitatively and quantitatively. Two representative piston rings, which belonged to the same two-stroke marine engine but were operated for different periods of time, were studied. Initial microstructural observations indicated a uniform distribution of graphite flakes on unworn surfaces, whereas worn surfaces demonstrated a tendency towards a preferred orientation. Approximately 40% of the open flakes of the unworn surfaces were closed during sliding, which may result in the deterioration of the self-lubricating capability of cast iron. Moreover, flakes within the orientation range of 0 to 30° relative to the sliding direction showed a maximum closing tendency when subjected to sliding. The closing tendency gradually decreased as the angle increased, approaching a minimum between 30 and 70°. A slight increase in the closing tendency was observed for flakes with orientations between 70 and 90°. A similar trend was observed on both rings. Furthermore, SEM and EDS analysis indicated substantial deformation of the matrix in the area around the flakes. An insignificant corrosion attack was observed on both worn piston ring surfaces.

  • 19.
    Ghasemi, Rohollah
    et al.
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Elmquist, Lennart
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Svensson, Henrik
    Swerea SWECAST AB, Materials and Process Development P.O. Box 2033, SE-550 02 Jönköping, Sweden.
    König, Mathias
    Scania CV AB, Materials Technology, SE-151 87 Södertälje, Sweden.
    E. W. Jarfors, Anders
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Mechanical properties of solid solution strengthened CGI2014Conference paper (Refereed)
    Abstract [en]

    The development of high-performing components is crucial in applications such as heavy vehicleautomotive powertrains. In these applications, strength, weight and thermal conductivity isessential properties. Key materials that may fulfil these requirements include cast irons of differentgrades where in terms of manufacturability and in particular, machinability pearlitic grades aredifficult due to hardness variation, where a fully ferritic matrix would provide an advantage. Toachieve maximum strength a fully ferritic and solid solution strengthened compacted graphite iron(CGI) would provide an interesting alternative to the automotive industry. In the current study, theeffect of Si level on mechanical properties in a fully ferritic material was investigated. The influenceof section thickness on tensile properties and hardness was investigated. The resulting materialwas fully ferritic with limited pearlite content. Section thickness influence on nodularity and hencethe mechanical properties were also investigated.

  • 20.
    Johansson, Glenn
    et al.
    Jönköping University, School of Engineering, JTH. Research area Industrial Production.
    Elmquist, Lennart
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Teaching international students: The value of having experience from teaching in a foreign country2012Conference paper (Other academic)
  • 21.
    Kasvayee, Keivan Amiri
    et al.
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Elmquist, Lennart
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Jarfors, Anders E.W.
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Ghassemali, Ehsan
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Development of a pattern making method for strain measurement on microstructural level in ferritic cast iron2014Conference paper (Refereed)
    Abstract [en]

    The current paper focuses on development of a method for studying micro-scale strains on the microstructure of ferritic cast iron. For this purpose, in-situ tensile tests were done under the optical microscope combined with digital image correlation (DIC). Critical in this development was to be able to achieve a reliable high spatial resolution of strain around microstructural features, such as graphite particles. Measurement of local strain fi elds in cast iron materials have so far been relying on displacement of naturally occurring microstructure patterns such as graphite particles, which limits the spatial resolution of strain measurement. In order to increase the spatial resolution of the measured strain, a pit etching procedure was applied to generate a random speckle pattern on the ferritic matrix. Th e critical challenges of in-situ investigation of microstructural deformation were identifi ed as speckle pattern quality and accurate selection of subset size and strain window size. Th e traceability of this method was studied by benchmarking the measured elastic modulus with that obtained from full-scale tensile test. Th e elastic modulus calculated from average strains, measured by DIC, showed a good agreement with material’s elastic modulus. Th is validates the measured localized strain values and can be used as a validation for modeling of local deformation.

  • 22.
    Matsushita, Taishi
    et al.
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Saro, Albano Gómez
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Elmquist, Lennart
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Jarfors, Anders E.W.
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    On the thermal conductivity of CGI and SGI cast irons2018In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 31, no 3, p. 135-143Article in journal (Refereed)
    Abstract [en]

    The thermal conductivity of Compacted Graphite Iron (CGI) and spheroidal graphite iron (SGI) was established in the temperature range from room temperature up to 500 °C using the experimental thermal diffusivity, density and specific heat values. The influence of nodularity, graphite amount, silicon content and temperature on the thermal conductivity of fully ferritic high-silicon cast irons was investigated. It was found that the CGI materials showed higher thermal conductivity than the SGI materials. The thermal conductivity tended to increase with increasing temperature until it reached a maximum followed by a subsequent decrease as temperature was increased up to 500 °C. Conventional models were applied to estimate thermal conductivity and the predictive accuracy of each model was evaluated. The thermal conductivity could be estimated by the Helsing model. The Maxwell model, Bruggeman model and Hashin–Shtrikman model were also in fair agreement using the thermal conductivity value of graphite parallel to the basal planes in graphite. 

  • 23.
    Orlenius, Jessica
    et al.
    Jönköping University, School of Engineering, JTH, Mechanical Engineering. Jönköping University, School of Engineering, JTH. Research area Component Technology.
    Elmquist, Lennart
    Jönköping University, School of Engineering, JTH, Mechanical Engineering. Jönköping University, School of Engineering, JTH. Research area Component Technology.
    Diószegi, Attila
    Jönköping University, School of Engineering, JTH, Mechanical Engineering. Jönköping University, School of Engineering, JTH. Research area Component Technology.
    Influence of Melting Process on Hydrogen and Nitrogen Content in Gray Iron2007In: Transactions of the American Foundry Society: One Hundred Eleventh Annual Metalcasting Congress May 15 - 18, 2007, Schaumburg, Ill.: American Foundry Society , 2007, Vol. 115, p. 617-623Conference paper (Refereed)
    Abstract [en]

    High concentrations of hydrogen and nitrogen in molten gray iron increase the risk of porosity in castings. Therefore, equilibrium variations of these gases at different stages in the process chain from melting to casting have been mapped. Both hydrogen and nitrogen content are affected by the melting method. The amount of hydrogen is also sensitive to the dwell-time in ladles and holding furnaces. The total amount of nitrogen, i.e. bonded and dissolved nitrogen, is not significantly affected by the temperature, while the hydrogen content is indirectly affected because of the relationship between dwell-time and temperature.

  • 24.
    Soivio, Kaisu
    et al.
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Elmquist, Lennart
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Influence of inoculation on shrinkage defects in spheroidal graphite cast iron2013In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 26, no 4, p. 220-227Article in journal (Refereed)
    Abstract [en]

    Defective castings produce unnecessary costs for foundries. Common flaw in spheroidal graphite cast iron castings are shrinkage defects. In literature it is suggested that by controlling the graphite precipitation it is possible to suppress the shrinkage propensity of the melt. The most influential way of effecting the graphite precipitation is inoculation. In this work the effectiveness of different commercial inoculant products and inoculation methods in reducing the shrinkage defects on cast component were researched. Significant difference in performance was observed between ladle and stream inoculation methods in preference of stream inoculation. Differences were also seen between different inoculants and how they behaved in combinations when ladle and stream inoculants were added simultaneously. It was observed that not all of the combinations were beneficial. In order to decrease the cost caused by shrinkage defects a proper selection of inoculation method and inoculant is of importance.

  • 25.
    Svensson, Ingvar L
    et al.
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Seifeddine, Salem
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Elmquist, Lennart
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Sjölander, Emma
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    Sjögren, Torsten
    Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting.
    On characterization and modeling of mechanical properties of materials for cast components2012Conference paper (Refereed)
1 - 25 of 25
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